Circuit breaker



` R- J. D. ROBERTS CIRCUIT BREAKER Filed lay 15. 1958 Nov' 17 Mn van,

@fw m mf T8 7. E l WR ,M a a J M ud w w W nited States Patent O CIRCUITBREAKER Ray J. D. Roberts, Chicago, lll., assignor to Charles D. Hummel,Sr., New York, N .Y.

Application May 15, 1958, Serial No. 735,430

7 Claims. (Cl. 200-11'55) My invention relates to an improved circuitbreaker and, more particularly, to a trip-free thermostatically operatedcircuit breaker of compact and rugged structure which is readilyinsertable into an electric circuit to prorect that circuit againstoverload.

Although the art relating to circuit breakers is extensive, a circuitbreaker embodying my invention and constructed in accordance with theprinciples thereof is singularly eective, sure in operation and yetcompact and inexpensive to manufacture. My invention contemplates theuse of a switch normally biased to its open position and adapted readilyto be connected into an electric circuit, and has a latching mechanismfor holding the switch in its closed position until released by heat orexcessive current ow.

In the disclosed switch, I have provided a temperature responsive latchin which the latching element is movable along the temperatureresponsive element in the direction of switch contact movement with oneof the switch actuating parts and is movable by the temperatureresponsive element in a direction lateral to that of switch contactmovement to and from a latching position, whereby the latching elementmoves with the switch actuating element when the contacts are manuallyoperated and is held away from the latching position by action of thetemperature responsive element,

A circuit breaker constructed in accordance with my invention is wellsuited to being built into a compact connector unit quickly connectibleinto the circuit for the protection of household appliances, either tobe furnished with an appliance or as a separate component. The structureand arrangement of parts in my circuit breaker is such that it avoidsthe necessity of a high degree of precision in either the manufacture ofparts or the assembly, and, thus, a circuit breaker incorporating myinvention may be inexpensive, durable and well suited to household use.

Other objects and advantages of my invention will be apparent from thefollowing description and the several views of the drawings, wherein: Y

Fig. l is a perspective view of a combination electrical connector plug,circuit breaker and receptacle embodying a preferred form of myinvention;

Fig. 2 is a side elevation of the device of Fig. l as seen` with thenear half of the housing removed and the circuit breaker in its circuitclosing position;

Fig. 3 is a view similar to Fig. 2, but showing the circuit breaker inits open position;

Fig. '4 is a transverse central section through the device takensubstantially on the line 4-4 of Fig. l looking in the direction of thearrows and illustrating the parts of the circuit breaker in their normalcircuit closing positions;

Fig. 5 is a view similar to Fig. 4 showing the circuit breaker in itsopen position;

Fig. 6 is an exploded view of the circuit breaker latching and` tripmechanism; and A Fig. 7 is a fragmentary longitudinal section ythrough2,913,552 Patented Nov. 17, 1959 ice the circuit breaker mechanism andis taken substantially at the position of the line 7-7 of Fig. 4,looking in the direction of the arrows.

The exemplary embodiment of my invention which is disclosed herein forillustrative purposes includes a housing 10 divided longitudinally intotwo separable parts 11 and 12 and desirably made of an insulatingmaterial, such as hard rubber or a strong thermo-setting plastic. Thehousing is generally rectilinear and has two holes 14 in predeterminedspaced relationship to one another in one end to provide for theinsertion of connecting prongs of another device, and has prongs 16extending from the other end of the housing, prongs which are for makingelectrical connections to a source of power such as an electric outlet,an extension cord or the like. A head 18 of a re-set button 20 extendsthrough appropriate facing channels 21 in the housing parts to protrudeoutwardly of the housing on one side thereof.

Interiorly, the housing parts are formed to provide, when assembledtogether, adjacent chambers 22 and 24 separated by a partition 26 whichhas an aperture 28 therein.

A conductor strip 30 has a contact end 32 in the `form of a prongextending into one of the holes 14 to make contact with a prong of aplug-in connector inserted into hole 14 from the end of the housing, theconductor strip following an outwardly offset path in appropriateopposed Agrooves in the housing parts to terminate at its other end inthe chamber22 on one side of the re-set button 20, and has a contact 34mounted thereon and secured thereto at the end within the chamber. Onthe other side of the re-set button in the chamber 22, a second contact36 is secured to the end of the conductor strip which follows a patholset inwardly in appropriate facing grooves in the housing halves toterminate in one of the plug-in prongs 16.

The other prong 17 and a receptacle contact 42 are parts of a unitary insub-assembly, as shown at the lower portion of Fig. 6. The prong 17consists of a conductor strip oifset outwardly inside the housing 10 inappropriate grooves and terminates at 44 in the chamber 24. Thereceptacle contact 42 is likewise a conductor strip offset outwardlyinside the housing 10 and terminating in the chamber 24 of the housing10 in aligned and spaced relationship to the end 44 of prong 17. Arectangular bimetallic plate 48 has integral ears 50 extending in rightangular relationship from the corner portions of one edge thereof. Theears are secured by means such as rivets 52 to the inner end 44 of theprong 17 and the inner end 46 of the receptacle contact 42. Thebimetallic plate thus stands upright relative to the prong and contactwithin the chamber 48 and is olfset with respect to the longitudinal.center line of the housing 10.

A latching strip 54 extends across the inside face of the bimetallicplate 48 and end portions 56 thereof are bent around the edges of thebimetallic plate and against the outer face thereof to mount thelatching strip on the bimetallic plate for vertical sliding movement.The latching strip includes a tongue 58 onr the upper edge thereofextending inwardly at right angles thereto.

The re-set button 20 has, inwardly ofthe head 18 thereof, an integralflange 60 thereon which projects radially of the head 1S, and alsoincludes a shank 62 below the iiange 60 and which, in the structureshown, has a diameter less than that of the head 18. The collar 60,among other purposes, serves to hold the re-set button 2t) within thehousing 10, it being too large to pass through the channels 21 throughwhich the head 18 extends. A bridging contact 64 consists of a striphaving contacts 66 atrits ends spaced to engage-contacts 34 and 36 onstrips 30 and 38. The strip as shown in Fig. 6, has a central portion 68which is otfset downwardly from the end pora tions thereof, and has acentral bore 7b therein through which the Vshank 62 of the re-set button20 extends. A coil type compression spring '72 encompasses the shank 62and is contained between the collar 60 and the bridging contact 64 ofthe re-set button 2li. Y

My device'likewise includes a sleeve 74 having an internaldiametersuicient to receive slidably the shank 62 of the re-set button20. Between its ends the sleeve has a transverse slot76 therein whichextends into the sleeve appreciably further than the thickness of thesleeve wall.

The re-set mechanism further includes a metal insert 78 which has a baseportion of cylindrical form and has an upper end portion 5) of smallerdiameter so as to provide a shoulder 32 between the portions. Thediameter of the base portion of the insert is such as to lit closely butslidably within sleeve 72.

A second coil compression spring 34 serves as another part of the re-setmechanism and is contained between the lloor 86 of the lower cavity 24and the bottom end of the insert 78 within the sleeve 74. The floor S6of the lower chamber is recessed as at S8 and the insert 7S is recessedas at t) to contain the ends of the spring 84.

As was stated before, the bimetallic plate 43 is offset from the lateralcenter line of the switch housing. Housing part lll which contains thebimetallic plate 4S is recessed appreciably away from the plate surface,as at 92 in the lower chamber 24, in order to permit outward ilexing ofthe plate when heated.V

The operation of the disclosed switch is as follows.

The normal, current conducting or closed position of the switch isillustrated in Figs. 2 and 4. The bridging contact 64 is closed againstcontacts 34 and 36 so as to establish an electrical circuit betweenprong 16 and receptacle contact 32. The device will be mounted to a walloutlet, for instance, by prongs i6 and 17 and the prongs of an appliancecord inserted into the holes 14 to make contact with receptacle contacts32 and 42. As the appliance is used, a circuit'is closed through prong38 and `receptacle contact 32 by the bridging contact 64, and throughthe associated prong of the appliance cord, the applianceandY the otheror return circuit is made through receptacle contact 42, the bimetallicplate 4S and prong 44. n

Under normal' load conditions the bimetallic plate 48 is relativelyunheated Vand, therefore, stands verticallyy without material exure. Byvirtue of this vertical position the tongue 58 of the latching strip 54extends into slot 76 of sleeve 74 and is hooked over the shoulder 82l ofthe metal insert 78. The insert is maintained in its uppermost positionby the coil spring S4. Therefore, the latching strip has been carriednear the upper edge of plate 48 and the tongue, in turn, has carriedsleeve 74 upwardly against the underside of the bridging contact 64 tohold the contacts 66 thereof against contacts 34 and 36. The bridgingcontact so seated acts as a stop for movement of the sleeve. i

In the event that the circuit is overloaded, excessive current will flowthrough the switch parts, including the Vcarrying with it the tongue 53of the latching strip, which slides downwardly on the plate 4S. As thesleeve is thus withdrawn from supporting relation to the bridgingcontact 64, spring 72 likewise drives the bridging contactI along shank62 of the re-set button 20 to withdraw it from circuit closingrelationship with the contacts 34- and 36.

The circuit breaker of my invention cannot be re-set as long as thebimetallic plate remains hot since the tongue 5S will be withheld frompossible engagement with shoulder 82 of the metal insert.

When the plate cools and thus urges tongue 58 further into the slot 76,the device may be re-set. The head of the re-set button is depressed,whereupon the end of the shank 62 forces the metal insert 78 downwardlyagainst the force of spring 84 until the tongue 58 again engagesshoulder 82 of the insert. Upon release of the force applied to there-set button, spring S4 forces insert 78 upwardly carrying tongue 58and, therefore, sleeve 74 with it to restore the bridging contact toCircuit closing position. The movement of the insert likewise drives there- Y set button Ztl back to its normal position.

Having thus describedmy invention, what I claim as new and desire tosecure by Letters Patent of the United States is: y

l. A combination attachment plug, overload circuit breakerandrreceptacle comprising a body, a pair of4 connector prongs at one endof said body, said body including a Vreceptacle portion having contactmembers therein, means including a switchrelement movable between openand closed positions for opening and closing a connection between one ofsaid connector prongs and one of said contact members, said switchelement being biased to its open position, means including a` bimetallicplate providing an electrical connection between the other of saidprongs and the, other ofV said contact members, means abutting againstsaid switch element and movable to effect movement of said `switchelementto said closed` position, a latch element'having a portionengaging said movable` means and slidably mounted on said 'bimetallicplate for movement with said movable meansha member normally movablerelative to the last mentioned movable means and having a portionnormally'V engageable by said portion of the latch element, the lastmentioned member being biased to urge said latch element and saidmovable means in one directionto elect movement of the switch element tosaid closed position when said portion of the latch element engages saidportion of the movable member, said latch element engaging said memberduring ilow to effect disengagement of said member by said por-- tion ofthe latch element from said portion of the movable member to releasesaid movable member and movable means to etfect movement of the switchelement to.

said open position.

2. The combination as set forth in claim l, and including additionalmeans operable from the exterior of the body and engageable with saidmovable member to move said member against the bias thereof to effectreengagement of said portion of the latch element and said latchengaging portion of the movable member.

3. A circuit breaker comprising a switch having separable contactsbiased to an open position, means for connecting said switch in anelectrical circuit, a bimetallic plate normally connected in seriesrelationship to said contacts for the transmission of current, contactactuating means movable to eiect closure of the contacts of said switch,a latch continuously engaged with said movable contact actuating means,said latch being mounted on said bimetallic plate for sliding movementrelative thereto as said contact actuating means is moved, Va membernormally movable relative to said contact actuating means and having aportion normally engageable by said latch, means normally biasing saidmember ina direction to movesaid latch and said movable contactactuating meansV to effect closure of the separablecontacts when thelatch is engaged with said member, said latch being engageable with saidmember during normal current ow through said plate, and said bimetallicplate being flexed tovdisengage Y said latch from said member byexcessive current flow through said plate` 4. The combination as setforth in claim 3, additionally including manually operable meansengageablewith'said member to move said member against the force of saidbiasing means thereon to eiect re-engagement of said latch and saidmember when said bimetallic plate is in its normal unflexed position.

5 A circuit breaker comprising a switch having relatively movablecontact elements biased to an open position, means for connecting saidswitch in an electrical circuit, actuating means movable to close saidcontact elements, a bimetallic plate normally having a positionsubstantially parallel to the direction of movement of said movableactuating means, a latch continuously engaged with said movable meansand slidably mounted on said bimetallic plate for movement along thebimetallic plate with said movable actuating means, a member normallymovable relative to the movable actuating means and having a latchengaging portion, means biasing said member in a direction to move saidlatch and said movable actuating means to effect closure of the contactelements when the latch is engaged with said member, said latch beingnormally disposed to engage said member when the bimetallic plate is inits normal position, said bimetallic plate being flexed by excessiveheat to eifect withdrawal of said latch from engagement with saidmember.

6. A circuit breaker comprising a housing, a switch in said housinghaving a movable contact element biased to open position, means forconnecting said switch in an electrical circuit, a tubular member havingone end abutting against said movable contact element and supported insaid housing for axial movement in a direction corresponding to thedirections of movement of said movable contact element, a bimetallicplate having a normal position substantially parallel to the directionof movement of said tubular member, a latch engaged with said tubularmember and carried on said bimetallic plate for sliding movements in thedirection of movement of said tubular member, a latch engaging memberslidably mounted in said tublar member for axial movement therein, saidlatch engaging member having a #latch engaging portion, means biasingsaid latch engaging member axially of said tubular member and in thedirection for effecting movement of the movable contact element lto aclosed position, a reset button operable from outside the housing andhaving a portion thereof within said tubular member, said re-set buttonbeing movable into contact with said latch engaging member to move saidlatch engaging member against the biasing force acting thereon, saidlatch having a normal position when the bimetallic plate is normallyunilexed by heat for engaging the latch engaging member -to support saidtubular member and latch engaging member in positions for holding themovable contact element in the closed position, and said bimetallicplate being ilexed by heat to withdraw said latch from said latchengaging member to release said latch engaging member, said tubularmember and said movable contact element from movement to the openposition by the biasing force on the contact element.

7. A circuit breaker for connection in an electrical circuit comprisingcontact means having open and closed positions, a sleeve longitudinallymovable to close said contact means, said sleeve having a transverseslot therein, means biasing said contact means and said sleeve topositions for opening of the contact means, a bimetallic elementnormally extending in a direction generally parallel to the direction ofmovement of said sleeve, a latch slidably mounted on said bimetallicelement and having a portion normally extending into said slot in thesleeve and into the interior of said sleeve, a shouldered element insaid sleeve, said latch normally engaging the shoulder of said element,means biasing said shouldered element oppositely to and more stronglythan rst mentioned biasing means to move said latch and said sleeve topositions for closing said contact means, said bimetallic element beingoriented to withdraw said latch from engagement with the shoulder ofsaid shouldered element upon exure resulting from the heating thereof,and means operable to move said shouldered element against said secondbiasing means to eiect re-engagement of said latch with said shoulderedelement.

References Cited in the file of this patent UNITED STATES PATENTS1,492,967 Donle May 6, 1924 2,824,191 Christensen Feb. 18, 1958 FOREIGNPATENTS 680,472 Germany Aug. 30, 1939

